Photoactivation of dichloro(ethylenediamine)platinum(II)

Photolysis of dimethylsulfoxide (dmso) solutions of the compound Pt(en)Cl₂, where en=ethylene-1,2-diamine, leads to solvolysis of the complex and formation of Pt(en)(dmso)Cl⁺. The reaction follows clean pseudo-first-order kinetics with parallel photolytically activated and thermally activated paths. Both paths are first-order in both Pt(en)Cl₂ and solvent. Eyring analysis of the rate constants for 25 °C≤T≤55 °C yielded a Gibbs energy of activation of 96 kJ mol^?1 for the thermal pathway and no measurable activation barrier for the photochemical pathway. The quantum yield for the photochemical path is 0.22, as determined using ferrioxalate actinometry.